`[NiCl_(2){P(C_(2)H_(5))_(2)(C_(6)H_(5))}_(2)]` exhibits temperature dependent magnetic behaviour. The coordination geometries of `Ni^(2+)` in the paramagnetic and diamagnetic states are:

Options

A. Tetrahedral and tetrahedral
B. Square planar and square planar
C. tetrahedral and square planar
D. Square planar and tetrahedral

Answer

C

Explanation

In the given complex `NiCl_(2) { P(C_(2) H_(5))_(2)(C_(2)H_(5))}_(2),` nickel is in `+2` oxidation state and the excited state electronic configuration of `Ni^(2+)` ion in free gaseous state is

for the given four - coordinated complex to be of paramagnetic . it must possess unpaired electrons in the valence shell,To satisfy this condition , four lone pairs from the four ligands occupies the four `sp^(3)`- hybrid prbitals as

Therefore , geometry of paramagnetic complex must be tetrahedral . On the other hand , for complex to be diamagnetic there should not be any unpaired electrons in the valence shelll . this condition can be full filled by pairing of electrons in 3d - orbitals against Hund's rule as

The above electrons arrangement gives rise to `dsp^(2) ` hybridisation and therefore , square planar geometry to the complex .